By 10pm police officers had made 63 arrests - including two for GBH, three for assaulting a police officer, two for possession of an offensive weapon, nine for common assault and 26 in relation to drugs.

Six thousand police officers were drafted in for the first day of the carnival, while the figure will increase to 7,000 for the final day of the event, which is one of the largest operations in the Metropolitan Police force's calendar.

Earlier in the day three to four kilos of crack cocaine worth an estimated £300,000 that was destined to be sold at the carnival was discovered by police in a suitcase in the basement of a flat in Lewisham.

Four people - a man and a woman aged in their mid 30s, a second man aged 19 and a third man aged 51 - were arrested at the flat in Broadfield Road on suspicion of being concerned in the supply of drugs.

More than one million people are expected to attend the Caribbean celebration over the next two days.

Sunday is traditionally aimed at families but the warm weather was expected to have attracted larger crowds because of a wet forecast for Bank Holiday Monday.

Chief Superintendent Robyn Williams said the force's priority is to "facilitate a safe and vibrant carnival".

She said: "Carnival very much presents us with two extremes; those who want to enjoy the sound systems, cuisine and have a good time and those who use it as an opportunity to commit crime."

Some police officers were encouraged to get into the carnival spirit after getting covered in chocolate by the crowd.

The Chocolate Nation Mas float was followed by hundreds of people throwing liquid chocolate all over themselves as they danced along the streets.

Michelle Johns, 44, from Lincoln, who was watching the procession with her husband and two daughters, said the officers were quick to embrace the fun.

"As the float was coming round the corner the same police officers were being targeted," she said.

"The group was spraying the chocolate around and going right up to them and spreading it on the officers' faces.

"The officers were laughing the whole time - I don't think there was much they could do.

"It's brilliant fun. Everyone is friendly and having a great time."

Theresa Smith, 69, who lives in South London but is originally from St Vincent in the Caribbean, helped to make costumes for children joining the South Connections band which took part in the procession.

She said: "I love the carnival, I've come every year since 1987.

"For two days of the year the streets of London are mine as a West Indie.

"The Caribbean community comes together and we celebrate. Celebrate the diversity, the culture, the mix of nationalities in London.

"Today I helped the children but tomorrow is my day, I'll dress up in my costume, play in the band and be part of this great carnival."

Children's Day saw streams of family friendly floats make their way from Westbourne Park Underground station to Ladbroke Grove.

However, the thumping bass of the sound systems was as loud as ever as side streets were filled with dense crowds of people partying to blaring sound systems.

Twanna Allen, 37, who joined the crowds partying alongside a float, said it was "some of the best fun I've ever had in London".

"It's the first time I've joined in and I can't believe I haven't done it before," she said.

Organisers said this year marks the first milestone in the build-up to the event's 50th anniversary in 2016.

A number of business owners and residents have boarded up their properties on the carnival route in a bid to avoid damage.

A gang crime crackdown in the run-up to the party resulted in 157 arrests and the seizure of guns, drugs and thousands of pounds in cash.

As part of Operation Kent officers retrieved two machine guns and a handgun, crack cocaine and around £78,000 in cash.

Officers known as ''super-recognisers'' are primed to spot those banned from the event, as well as gangs and groups who attend.

However Ms Williams said the arrests did not indicate the level of crime expected at the event.

"The proactive, pre-emptive focus of the carnival was highly effective," she said.

"The success of the operation doesn't present a direct correlation of what may or may not happen.

"Th e most serious violent crime at the event has reduced over the years and considering the number of people here we have a relatively low crime rate."

However she warned visitors to be alert and take steps to reduce their vulnerability to low level crime by not wearing valuable jewellery or holding mobile phones on show and considering how much they drink.

Asked about the planning which goes into the police operation, she said: "Let me put it this way, on Tuesday morning we'll begin planning Notting Hill Carnival 2015."

Tomorrow the number of officers will be increased to 7,000 to reflect the "adult day" billed as the grand finale which boasts 60 bands.

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